Process of flocculating silica with a cationic xanthomonas gum ether

ABSTRACT

A CATIONIC XANTHOMONAS MICROBIAL GUM PRODUCED BY THE REACTION OF A QUATERNARY AMMONIUM COMPOUND AND A XANTHOMONAS MICROBIAL GUM DERIVED FROM THE AEROBIC FERMENTATION OF THE BACTERIUM XANTHOMONAS. THE CATIONIC XANTHOMONAS MICROBIAL GUM CAN BE SUITABLY USED AS A FLOCCULANT.

United States Patent Oflice 3,598,730 Patented Aug. 10, 1971 3,598,730PROCESS OF FLOCCULATING SILICA WITH A CATIONIC XANTHOMONAS GUM ETHERRobert Nordgren and Harold A. Wittcotl, Minneapolis, Minn., assignors toGeneral Mills, Inc.

N Drawing. Original application Apr. 15, 1968, Ser. No. 721,143, nowPatent No. 3,505,310. Divided and this application Dec. 10, 1969, Ser.No. 884,034

Int. Cl. B01d 21/01 US. Cl. 21054 3 Claims ABSTRACT OF THE DISCLOSURE Acationic Xanthomonas microbial gum produced by the reaction of aquaternary ammonium compound and a Xanthomonas microbial gum derivedfrom the aerobic fermentation of the bacterium Xanthomonas. The cationicXanthomonas microbial gum can be suitably used as a flocculant.

This application is a divisional application of our earlier filedcopending US. application Ser. No. 721,143, filed Apr. 15, 1968 now US.Patent No. 3,505,310.

This invention relates to a quaternary ammonium polysaccharide producedby the reaction of a Xanthomonas microbial gum and a quaternary ammoniumcompound. More specifically, this invention relates to the cationicpolysaccharide derived from a reaction of a Xanthomonas hydrophiliccolloid and 2,3-epoxypropyl trimethylammonium chloride.

Polysaccharide B-1459 is a polysaccharide gum polymer produced in anaqueous nutrient fermentation medium by the action of the microorganismXanthomonas campestris, B-l459. These Xanthomonas hydrophilic colloidsare known for a wide variety of uses such as additions to drilling muds,thickening agents, fortifying agents for candies, etc. It has now beenfound that a specific cationic Xanthomonas microbial gum is a verysatisfactory flocculating agent. By flocculating is meant the process ofconverting finely divided or colloidally dispersed suspensions of asolidinto particle sizes which settle rapidly. It has also been foundthat a cationic quaternary ammonium Xanthomonas microbial gum willflocculate where noncationic microbial gums produce no flocculation.This invention in its broadest sense encompasses the Xanthomonasmicrobial gums which are reacted with quaternary ammonium compoundspreferably 2,3-epoxypropyl trimethylammonium chloride to give a cationicXanthomonas hydrophilic colloid.

When practicing a preferred embodiment oft his invention, theXanthomonas hydrophilic colloid referred to as Bl459, which is producedby Xanthomonas campestris, is reacted with the quaternary ammoniumcompound as disclosed herein. The product of this reaction is a cationicXanthomonas hydrophilic colloid which will rapidly flocculate finelydivided silica under acidic conditions.

The quaternary ammonium microbial gums are provided by reacting theXanthomonas microbial gum with reactive quaternary ammonium compounds.The quaternary ammonium compounds particularly suitable for thisinvention may be defined by the following formula wherein R R and R arefrom the group consisting of alkyl, substituted alkyl, alkene, aryl andaralkyl groups, Z is an anion and R is a divalent alkylene radical of1-3 carbon atoms. Illustrative thereof are --CH CH CH -CH CH CH and CHZCOH- Particularly preferred is the quaternary ammonium compound known as2,3-epoxypropyl trimethylammonium chloride.

If all R R and R are the same, they each should preferably contain notmore than 4 carbon atoms. If all three are not the same and if Rcontains up to 18 carbon atoms then R, and R should preferably be fromthe group of methyl and ethyl. If R and R are joined to form. a ringthen R, should preferably be from the group of methyl and ethyl. Thusthe total number of carbon atoms in R R and R should preferably notexceed 22 carbon atoms and may contain as low as 3 carbon atoms.

The quaternary ammonium compounds may be prepared by reacting a tertiaryamine or tertiary amine salt with an epihalohydrin. Tertiary amineshaving the groups R R and R defined above may be employed. The epihalohydrin employed is one providing the group R, defined above. If atertiary amine is employed, R is an alkyl group, which contains theepoxy group. If a tertiary amine salt is employed, R is a halohydringroup. Illustrative tertiary amine salts are the salts prepared bytreating a tertiary amine with hydrochloric acid, sulfuric acid orphosphoric acid.

The preferred tertiary amines are those possessing at least two methylgroups, R and R attached directly to the nitrogen atom because of theirgreater reactivity which is maintained even when the third group, Rcontains as many as 18 carbon atoms as in dimethyl stearyl amine. Othertertiary amines which may be employed are dimethyl benzene, dimethyldodecyl, dimethyl decyl, diethyl stearyl, diethyl dodecyl, diethylbenzene amine, triethyl amine, tripropyl amine, tributyl amine, N-ethyland N-methyl morpholine, N-ethyl and N-methyl piperidine and methyldiallyl amine.

To prepare the quaternary ammonium compounds, the reagents may beprepared by simply mixing equimolar quantities of the epichlorohydrinand the tertiary amine or the salt thereof, in an aqueous system andallowing the reaction to proceed preferably with agitation untilformation of the product is complete. When employing -the salts, bestresults are obtained if the pH of the aqueous system is above 8 andpreferably between 9 and 10. The resultant addition product is thenrecovered by removal by vacuum distillation of the unreactedepihalohydrin and amine.

For illustration, the reaction of epichlorohydrin and tri methylaminemay be shown by the following equation:

In order to prepare the quaternary ammonium microbial gum ethers of thisinvention, the above described quaternary ammonium compounds may bedissolved in a suitable solvent such as water, dioxane, or an alcohol,and the microbial gum, preferably Xanthomonas campestris, B-l459, addedthereto. Any inert solvent may be employed. Among the suitable alcoholsare isopropanol, ethanol, and tertiary butanol. A strongly alkalinecatalyst is generally employed to promote the reaction. The reactionoccurs at room temperature; however heat and inacreased amounts ofcatalyst increase the reaction rate. In general, temperatures of atleast 30 C. and up to 100 C. may be employed. The catalyst whenemployed, is preferably not employed in excess of 0.2 mole. Suitablecatalysts are the alkali metal hydroxides, alkali earth hydroxides andquaternary ammonium basis such as sodium hydroxide, lithium hydroxide,potassium hydroxide, calcium hydroxide, ammonium hydroxide, and benzyltrimethyl ammonium hydroxide. After the etherification reaction, thecatalyst may be left in the reaction product or neutralized with anysuitable acid such as acetic or hydrochloric acid. The cationicXanthomonas microbial gum ether of a quaternary ammonium compound maythen be dried for use in powder form. The quaternary ammonium compoundis preferably employed in an amount of from .05 to 0.2 mole per molarweight of anhydrogluclose unit; however amounts from 0.02 to 0.3 arealso useful. By varying the amount of quaternary products, varyingdegrees of substitution (D.S.) are provided.

Suitable microbiological polysaccharides are those produced by themicrobial fermentation of glucose sugar with the bacterium Xanthomonas,especially the species Xanthomonas campestris. These microbiologicalpolysaccharides are normally produced by inoculating a medium containingfrom about 1 to about 5% by weight of a suitable carbohydrate, organicnitrogen sources, dipotassium hydrogen phosphate and appropriate traceelements, with an organism of the genus Xanthomonas and then permittingthe culture to incubate at about room temperature and under aerobicconditions for a period of about 3 days. Carbohydrates which may beemployed in this manner include glucose, fructose, maltose, sucrose,lactose, galactose, and the like. While the X a-ntho monas campestris isthe bacterium preferred, other related species of Xanthomonas may besatisfactorily used. Such other species are Xanthomonas begoniae, X.vesicatoriw, X. malvacearum, X. incanae, X. vasculorum, X. carotae, X.lranslucens, etc. At the end of the incubation period, the crude polymerformed in the culture medium can be separated from the bacterial cellsby filtration and thereafter isolated and purified by precipitation withmethanol, ethanol, acetone or a similar reagent. After drying, themicrobiological polysaccharide is recovered as a light fluffy powderwhich may be slightly tainted by colored materials from the culturemedium. Suitable methods of producing a microbiological polysaccharideare disclosed in US. Pat. 3,000,790 and the following articles:

Information on Polysaccharide B-1459, Northern Utilization Research andDevelopment Division, US. Department of Agriculture, Peoria, 111., No.Ca-N9, September 1959.

New Polysaccharide Gums Produced by Microbial Synthesis, ManufacturingChemist, May 1960.

Journal of Biochemical and Biological Technology and Engineering, vol.III, No. 1 (S. P. Rogovin et al.).

The dried cationic Xanthomonas hydrophilic colloid may be used as aflocculant to remove finely divided substances, such as silica, fromslurries. Other embodiments and uses of the product of this inventionwill be readily apparent to those skilled in the art.

The following examples will further illustrate but are not intended tolimit the scope of this invention.

EXAMPLE I The following reactants were placed in a flask fitted with athermometer, stirrer, and a reflux condenser.

Microbiological polysaccharide, X anthomonas campestris,

Bl459-- grams Isopropanol 99%150 grams Sodium hydroxide (2 gramsdissolved in 70 milliliters of water)70 milliliters 2,3-epoxypropyltrimethylammonium chloride (57% in water)26.8 grams The reactants werestirred and gradually heated to a reflux temperature of 81 C. and thenmaintained under reflux for 2 hours. After the 2 hour period, thealkaline catalyst was neutralized with 3 milliliters of acetic acid. Thereaction product was filtered, washed with isopropanol, and dried at 60C. The dried product was analyzed and found to have a dry weight gain of14 grams. The percent nitrogen on the reacted microbiologicalpolysaccharide was found to 'be 1.99% while on the unreactedmicrobiological polysaccharide it was 1.22%. These results indicated adegree of substitution of 0.1-0.18 mole of 2,3-epoxypropyltrimethylammonium chloride per monomer unit of the microbiologicalpolysaccharide gum, B-l459. In this manner, a highly active cationicpolymer was produced.

EXAMPLE II To show the flocculating properties of the above cationicgum, two 100 milliliters samples were prepared as follows Amount, gramsHydrated silica, average particle size 0.022 micron 0.5 HCl 18 Water 82To one of the samples, there was added 10 milliliters of a 0.5% aqueoussolution of a cationic microbial gum of Example I. Within 3 minutes, thesilica in the above solution was fiocculated and settled. To the othersample, there was added a 0.5% aqueous solution of the noncationic,unreacted microbial gum B-1459. The nonreacted or non-cationic B-1459had no effect upon the silica.

The cationic microbial gums as disclosed herein can be satisfactorilyused in any process where it is desired to have a charged colloid, i.e.sizing of paper, textiles, etc. Also, it is beneficial to use a cationicmicrobiological polysaccharide in many thickening operations. Other usesof this cationic microbiological polysaccharide will be readily apparentto those skilled in the art.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A process of flocculating a solution containing finely divided silicaparticles comprising acidifying said solution and treating saidacidified solution with a cationic Xanthomonas gum ether of a quaternaryammonium compound.

2. The process of claim 1 'wherein the quaternary ammonium compound is2,3-epoxypropyl trimethylammonium chloride.

3. The process of claim 1 wherein said solution is acidified withhydrochloric acid.

References Cited UNITED STATES PATENTS 3,244,695 4/ 1966 Schweiger260-209 3,376,282 4/1968 Schweiger 260209X 3,406,114 10/1968 Goren 210543,418,237 12/1968 Booth et al 210-54 3,422,085 l/ 1969 Gill et a1260-209 3,467,647 9/1969 Benninga 21054X MICHAEL ROGERS, PrimaryExaminer U.S. Cl. X.R.

